Chain hoists are widely used throughout the world to lift and lower heavy objects. Basically, a chain hoist includes a load chain that is designed to connect to the load and a drive chain that is operative to raise and lower the load chain and the load connected thereto. The chain hoist includes a reduction gear network that is operatively connected between the drive chain and the load chain. Thus, very heavy loads can be moved upwardly or downwardly by a relatively small amount of force.
Many of the chain hoists that are operating today are of the manual drive type. That is, the drive chain is manually pulled by a person as opposed to the newer chain hoists that are electrically driven. Surprisingly, there are large numbers of manual hoists in existence and being used today. The amount of energy required to drive these chain hoists is substantial. This is particularly true in applications where individuals operating these manual chain hoists are required to repeatedly and continuously manually drive them. It is not unusual for this strenuous work over time to result in back and other injuries.
It is known, however, to provide chain hoists with electric drives. For example, in the patent to H. B. Newhall, U.S. Pat. No. 1,468,916, there is shown a chain hoist that is powered by an electric motor. However, the electric motor is mounted on a frame and suspended from the drive chain by a pulley or drive member that is driven by an interconnecting gear network. In the end, such drive systems are heavy, bulky and certainly difficult to transport from one location to another.
Therefor, there has been and continues to be a need for a portable light weight power assembly for driving manual chain hoists that can be easily transported from one location to another.